Many types of equipment require some means of temperature control, either by heating or cooling, in order to function effectively. In general, such equipment consists of three elements: the component requiring temperature control, a heat transfer (device, and a medium acting as a thermal energy sink or source. Some equipment, such as those which transfer heat from one medium to another, require heat transfer devices for supplying and removing heat.
In general, equipment which require small amounts of, or low watt-density, cooling use natural or forced convection air cooling. On the other hand, equipment which requires large amounts of, or high watt-density, cooling, or precise temperature control, or operating temperatures at or below ambient air temperature use something other than air for cooling. Such techniques incorporate liquid cooling, thermoelectric cooling, or Freon compressor/condenser cooling.
In the home refrigerator, for example, heat is transferred from the inside of the refrigerator cabinet to the air outside. The refrigeration unit has two heat transfer devices. Inside the refrigerator there is typically an extruded air heat sink and fan which provides forced air convection to remove heat from the source medium, the air inside the refrigerator, and to transfer the heat to the refrigeration unit. Outside the refrigerator, heat from the refrigeration unit is transferred by an external radiator via natural convection into the heat sink medium, i.e., the surrounding air. However, for other applications which require a more efficient thermal energy transport system, liquids can readily provide the medium by which heat is transferred.
The transfer of heat by a liquid medium is often accomplished with a heat transfer plate, sometimes called a "cold plate". A cold plate is typically a flat metal plate in contact with a flowing fluid. Thermally conductive metals, such as aluminum or copper, are commonly used for the plate, although other metals, such as stainless steel, may be used in corrosive environments. Components requiring temperature control are mounted onto an exterior surface of the cold plate.
The thermal efficiency of the cold plate depends upon the amount of surface area of the cold plate in contact with the flowing fluid, the degree of turbulence of the flowing fluid, and the efficiency of thermal contact between the components and the cold plate. It is desirable for a liquid cold plate to have a high degree of thermal efficiency, while at the same time be simple and inexpensive to manufacture. Simple and low-cost manufacturing is commonly achieved with a cold plate formed by a flat aluminum plate with copper tubing glued or pressed into grooves in the surface of the aluminum plate. Such designs have very low surface areas in contact with the flowing fluid. On the other hand, high efficiency heat transfer is commonly achieved with cold plates which have a large amount: of surface area in contact with the cooling fluid. Such cold plates are typically either not flat and complex (e.g., shell and tube designs), or very expensive to manufacture (e.g., brazed plate-fin designs).
Thus the desire for cold plates which are simple and easy-to-manufacture at low costs conflicts with the desire for cold plates with high heat transfer efficiency. However, the present invention resolves these conflicting desires with a cold plate which has high heat transfer, but which is also simple and inexpensive to manufacture.